Waiting for the inbound aircraft in the Company office in New Delhi, Palam Airport early one foggy morning, the inbound Captain called on the Company radio, I took the call and he said that the ATIS was giving 200m. RVR. and he was holding at F/l 200 over the VOR, which was some 14 nm north of the field in those days - if I recall correctly - and it was all Cavok at that location, so what was the vis. on the field really like, as he had about 15 mins left before diverting to Bombay ( not Mumbai )
I replied that it really was very foggy but I didn't know what 200 m really looked like from my position, so would go over to the tower and find out. ( yes, one could ).
Reaching the tower a quasy-digital Indian design RVR meter was showing 200 m as broadcast, but as I looked it increased to 210, then 220 and eventually reached the legal limit - which I forget - but the controller said nothing. Eventually the RVR increased to be of no further consideration, the field became almost Cavok, as being experienced by the aircraft further North, but still the controller said nothing, so I tapped him on the shoulder and asked why he wasn't advising the holding aircraft to commence an approach ? " I cannot transmit an improvement in the visibility until it has been positively sustained for 10 minutes " he said.
I ran back to the office and advised the inbound Captain - a friend, whose voice I recognised - that the vis. was now well above minima - but they weren't going to tell him for 10 minutes, but if he requested a descent, by the time he got on to finals they would have ! A diversion saved.
Maybe the ATC controller was following the book, but my question later was - if the RVR was
reducing below legal minima one dark and dirty night, would they not tell me until 10 minutes after I had crashed on the field ?
